A stator of this kind is in the overall form of a body of revolution about the axis of the machine, this axis defining the "longitudinal" direction hereinafter referred to. It comprises, in a manner known per se, a magnetic circuit consisting of a stack, along the longitudinal direction, of thin metal sheets forming circular rings in transverse planes. The inner edge of the sheets is formed with angularly distributed notches to accommodate stator winding bars, the remaining sheet between two angularly successive notches constituting a tooth projecting radially inwards. The solid part of the sheets externally of the notches forms a "magnetic ring" conducting the stator magnetic flux in the circumferential direction.
This stack is clamped up by means of clamping fingers distributed angularly at both ends so as to exert a clamping pressure on the ring and each of the teeth. Each of these fingers is in the form of a strip of sheet metal having a radial length, a longitudinal height and a tangential thickness, an external part of the length of the finger extending over the magnetic ring and an internal part over one only of the teeth.
The clamping force is applied to these fingers by longitudinal rods which pass through the entire stack and to the ends of which nuts are fitted. These rods may not be placed in the teeth of the magnetic circuit, even if they are insulating, because of the necessity to retain a sufficient cross-section for the passage of the magnetic flux conducted by these teeth.
Thus they are always disposed in the ring. Unfortunately, in the case of many bulb sets, the height of this ring as measured radially is less than the depth of the notches. As a result, the clamping force applied to the fingers by these rods is incorrectly distributed by the fingers: the clamping pressure is too high on the magnetic ring and too low on the teeth. Also, irrespective of their position these rods are subject to induced current losses if they are of metal and reduce the magnetic steel cross-section available for the passage of the stator magnetic flux.
Finally, it is not a simple matter to maintain the clamping force, which tends to decrease with time in service, by virtue of the difficulty of access to the nuts. The space at the two ends of the magnetic surface is congested through the presence of the stator winding heads.
The objective of the present invention is to provide a laminated magnetic circuit stator with clamping fingers for a rotating electrodynamic machine, notably of the immersed bulb type, this stator overcoming the disadvantages of the clamping rods and providing a simple means for selecting the best distribution of the clamping force between the teeth and the magnetic ring and for checking and reclamping the magnetic circuit without any dismantling of the machine, this without creating undesirable bulk.